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RE: [Xen-devel] [VTD][PATCH] Do FLR of assigned devices with VT-d


Oh, now I see why you did that. I'm eager to test the PCI hotplug stuff :-)

The only thing that is concerning me is that it becomes VT-d specific.
And I still think that the hypervisor is a bad place to put that code...


> -----Original Message-----
> From: Han, Weidong [mailto:weidong.han@xxxxxxxxx] 
> Sent: Sunday, January 27, 2008 2:38 PM
> To: Guy Zana; xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: Xu, Anthony; Kay, Allen M
> Subject: RE: [Xen-devel] [VTD][PATCH] Do FLR of assigned 
> devices with VT-d
> Hi Guy,
> If you use "xm destroy" or click "x" on qemu window to 
> destroy guest, the assigned device may be stayed in a 
> incorrect status. We met that the irq of the assigned device 
> may be disabled by dom0 after destroy guest, then all the 
> devices using the same irq can't work any more. We also met 
> guest complained the device was not in a correct status 
> during its booting period.
> We think there are three places where need invoking FLR 
> function. The first place is before device assignment, the 
> second one is after exit/destroy guest, the last one is 
> dynamic reassignment after support vtd hotplug. In the latter 
> two cases, it is hard to catch the point to do FLR in qemu.
> Randy (Weidong)
> Guy Zana wrote:
> > That's a good addition, why moving this functionality to the 
> > hypervisor? BTW, can you give real world example where this was 
> > needed?
> > 
> > Thanks,
> > Guy.
> > 
> >> -----Original Message-----
> >> From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
> >> [mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Han, 
> >> Weidong
> >> Sent: Thursday, January 24, 2008 4:39 AM
> >> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> >> Cc: Xu, Anthony; Kay,Allen M
> >> Subject: [Xen-devel] [VTD][PATCH] Do FLR of assigned devices with 
> >> VT-d
> >> 
> >> Currently there is a pdev_flr() function to do FLR before device 
> >> assignment in qemu, but most of devices don't have FLR capability. 
> >> What's more, should do FLR before assignment and deassignment for 
> >> keeping correct device status. If the device doesn't have FLR 
> >> capablility, this patch implemented to enter D3hot and 
> return to D0 
> >> to do FLR. And exposed pdev_flr() in VT-d utils, then it can be 
> >> invoked by assignment and deassignment functions.
> >> 
> >> Signed-off-by: Weidong Han <weidong.han@xxxxxxxxx>
> >> Signed-off-by: Anthony Xu <anthony.xu@xxxxxxxxx

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